1. Field of the Invention
The invention relates to aspirators, and more particularly, to centrifugal aspirators capable of efficiently aspirating a conveying fluid containing solid particles.
2. Description of the Prior Art
Various aspirators, sump pumps, jet pumps, dredging devices, and the like, are known in the prior art. Some of the known devices, such as those shown in U.S. Pat. Nos. 3,856,651 and 4,028,009, operate to create vortexes having low pressure vortex "cores" creating suction which conveys fluid containing solid particles, such as slurry or dredged material, into the vortex. Various means are utilized to exhaust the conveying fluid and solid particles therein from the vortex. However, such known devices are expensive and complex. There exists a need for an efficient, yet inexpensive aspirator capable of aspirating a conveying fluid containing solid particles. One known aspirator, manufactured by Keene Engineering, called a suction nozzle, is a relatively simple device which can be connected to a suction hose or tube to aspirate or dredge gravel. Many amateur and professional prospectors use such devices while prospecting for gold. The suction nozzle contains a suction tube having an approximate 30.degree. bend, a suction inlet for drawing in dredged gravel and a connection to a hose for carrying a mixture of gravel and water to a sluice or the like. Water from a high pressure source is injected into the suction tube at the bent portion of the suction tube. However, this device, although inexpensive and simple, does not produce a suitably high level of suction, and is quite inefficient in that it requires a high ratio of volume of injected high pressure water to volume of dredged material.
It is therefore an object of the invention to provide an economical, simple aspirator which can aspirate or dredge conveying fluid containing solid particles with greater efficiency than aspirators of the prior art.
U.S. Pat. No. 2,565,907 discloses an apparatus which injects high pressure air tangentially into a vortex chamber, producing a low pressure vortex core which draws an aspirated fluid into the vortex and exhausts a mixture of the high pressure and an aspirated fluid (the term "fluid", as used hereinafter, can refer to either a gaseous fluid or a liquid fluid). This device, although simple and efficient (because of the characteristic low pressure vortex core), is unsuitable for dredging purposes or for aspirating any fluid containing solid particles because the solid particles are thrown centrifugally outward into the vortex chamber and therefore are not exhausted. Consequently, the device of U.S. Pat. No. 2,565,907 rapidly becomes clogged if used for dredging.
It is therefore another object of the invention to provide a simple, inexpensive aspirator which efficiently exhausts a fluid conveying solid particles having a higher specific gravity than the conveying fluid.
It is another object of the invention to provide a clog-free centrifugal aspirator.
U.S. Pat. No. 2,795,197 discloses an aspirator having a lower vortex chamber and an upper vortex chamber separated by a barrier, wherein tangentially injected high pressure fluid produces a vortex in the lower chamber to produce a vacuum which sucks the aspirated fluid into the lower vortex chamber. A mixture of the aspirated fluid and the injected fluid passes through a discharge orifice centrally disposed in the barrier separating the upper vortex chamber from the lower vortex chamber and is centrifugally exhausted by means of an exhaust port located in the cylindrical wall of the upper vortex chamber. This device, although simple and efficient for fluids which contain no solid particles, is totally unsuitable for dredging operations, because solid particles would rapidly clog the lower vortex chamber, thereby rendering the device inoperative.
It is another object of the invention to provide a centrifugal aspirator which avoids the problems of prior aspirators in dredging operations.